This invention relates to improvements in low-profile inline filters for use in intravenous (IV) sets and the like.
Low-profile inline IV filters are known in the art. These filters are generally connected in series with an IV tube to filter the fluid flowing through the IV tube before it enters a patient. These filters offer advantages over larger, bulkier filters, in that they can be conveniently located on the IV line at a site close to where the line connects to the patient. Therefore, they can be located without causing an obstruction to the manipulation of the IV line and the injection needle, and without presenting a bulky mass that can disturb the IV connection either by pulling on it with its own weight or by being bumped, pulled, or snagged.
Because, the low-profile inline filters are utilized to filter fluid before it enters the patient, great care must be taken so that the filters have no leaks, external or internal, at the points of connection of the various elements. These units must be hermetically sealed or the fluid entering the body may be contaminated causing infection or the spread of disease.
Low-profile inline filters are constructed from a plurality of parts. U.S. Pat. No. 4,400,277 to Leason discloses a low-profile inline filter constructed from two parts. These two parts comprise, a tubular housing shell unit, open at one end, and an elongated screen unit, which includes a cap portion. The screen unit is adapted to fit substantially within the tubular housing unit. The screen unit includes a ring member which seats on a stepped portion of the housing shell unit. The ring member and stepped portion, and the cap portion and opening of the housing unit must be sealed together. Typically, these units are sonically welded together to form a hermetic seal.
As stated above, because these units are utilized to filter fluids before they enter a patient's blood stream, the filter unit must be hermetically sealed. Accordingly, these filters must be tested to insure that a hermetic seal is present. The external seal between the cap portion and housing of the low-inline profile units are tested by passing fluid under pressure through the housing unit to see if they leak.
Especially difficult to test is the internal seal between the filter frame and housing. Because this is an internal seal and located near the inlet end it is very difficult to determine whether the required hermetic seal is present. Moreover, because this seal determines whether the fluid which enters the housing will be filtered or not it is extremely important that the requisite seal is present.
Typically, this seal is tested by passing alcohol under low pressure through the filter and determining whether bubbles are passing between the filter frame and housing. As can be easily appreciated, this is a very time consuming process and results in an increase cost for the filter and a limit on the number of filters which may be tested.
Thus, there is a need for a low-profile inline filter which is so constructed and arranged that one may readily determine whether an internal hermetic seal is present between the filter frame and the housing unit.